Powering the sustainable RNA therapeutics revolution with enzymatic synthesis

Holding immense promise for tackling a wide array of diseases, from rare genetic disorders to chronic conditions like heart disease, RNA-based therapies have quickly established themselves as a breakthrough in modern medicine. The RNA therapeutics market is projected to reach $18 billion by 2030, reflecting a fundamental shift toward broader, high-volume indications [1]. However, this rapid growth has exposed a significant bottleneck: manufacturing. The ability to deliver high-purity RNA constructs at scale, speed and sustainability has become the defining challenge for the industry.

For decades, the standard has been solid-phase oligonucleotide synthesis (SPOS) [2]. Although it is reliable, this legacy process, dependent on solid-phase workflows and hazardous chemicals, is fundamentally limited in its ability to meet modern demands for cost, scale and environmental responsibility.

The limitations of solid-phase synthesis

As RNA therapeutics transition to chronic, large-volume applications, the operational and environmental shortcomings of SPOS are becoming untenable and conflict sharply with modern environmental, social and governance (ESG) objectives.

The most pressing concern is the consumption of solvents. SPOS relies heavily on large volumes of flammable and hazardous organic solvents, generating a devastating amount of chemical waste. Traditional methods can result in a staggering Process Mass Intensity (PMI) of approximately 4,300 kg of waste per kilogram of active pharmaceutical ingredient (API) [3]. Managing and disposing of this waste incurs substantial costs and significant environmental risk.

Additionally, the harsh chemical reagents used in SPOS often generate undesirable side reactions and difficult-to-remove Class IV impurities. The presence of these impurities necessitates extensive, energy-intensive downstream purification, further escalating the environmental footprint. Operationally, scaling SPOS is capital-intensive, requiring specialized, explosion-proof infrastructure to safely handle and store these hazardous materials, exemplified by multi-million-dollar capacity expansion projects across the industry.

The scalable, pure and green solution

Enzymatic RNA synthesis is a transformative, next-generation solution. This innovative approach uses engineered enzymes to synthesize oligonucleotides under mild, aqueous conditions, thereby providing a greener and more efficient pathway for RNA production [4, 5].

Enzymatic methods overcome the intrinsic scale limitations of SPOS, which typically peaks at around 5 kg per run. Thanks to robust, engineered enzymes and solution-phase, modular designs, enzyme-enabled processes have demonstrated the ability to scale up to double-digit kilograms per run. This superior scalability and the capacity to run larger reaction volumes dramatically accelerate the manufacturing cycle, making it ideal for chronic, population-wide use.

Crucially, enzymatic workflows inherently provide enhanced purity and quality. By mimicking natural biological processes, they reduce the formation of undesirable byproducts and effectively minimize or eliminate problematic Class IV impurities. This higher purity reduces rework, simplifies downstream processing requirements and cuts material waste, directly improving the overall sustainability of the process.

Engineering for purity and efficiency

The cornerstone of this sustainable advantage is the shift from hazardous organic solvents to water. This eliminates the need for vast quantities of toxic chemicals, drastically reducing chemical waste, improving personnel safety and simplifying facility requirements.

Enzymatic synthesis platforms employ specialized approaches, all facilitated by highly engineered enzymes:

Sequential enzymatic synthesis employs a streamlined, two-step cycle to construct RNA strands one nucleotide at a time, thereby minimizing the number of chemical steps compared to the four-step cycle of SPOS.
Ligation-based assembly uses engineered RNA ligases to join pre-purified, shorter fragments into complex, longer constructs. This modularity avoids the cumulative yield losses and waste inherent in extended stepwise SPOS, significantly simplifying purification demands.

This success is underpinned by enzyme engineering, which develops tailored enzymes with robust catalytic performance and tolerance for complex RNA modifications. This targeted approach minimizes unwanted side reactions and reliably supports scalable, GMP-ready production.

Driving cost-effectiveness and defining the future

The enhanced efficiency and sustainability of enzymatic synthesis directly translate to significant cost-effectiveness. By drastically reducing the reliance on expensive solvents and minimizing chemical waste disposal and purification requirements, operational costs are substantially lowered. Higher yields and accelerated production timelines ensure a more efficient use of resources and capital. The future of RNA manufacturing will be defined by:

Hybrid approaches
Combining the strengths of SPOS for short fragments with enzymatic ligation for assembly.
Continuous innovation
Ongoing enzyme refinement for even greater efficiency and tolerance to complex modifications.
Regulatory alignment
The inherent principles of green chemistry align perfectly with global ESG trends and evolving regulatory guidance on process efficiency.

By embracing these enzyme-enabled solutions, the biopharmaceutical industry can ensure that RNA therapeutics are produced responsibly, affordably and are accessible for a global patient population, securing a healthier future for healthcare and the planet.

References

1. https://www.marketsandmarkets.com/ResearchInsight/rna-therapeutics-market-size-and-share.asp
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC6270087/
3. https://pubs.rsc.org/en/content/articlelanding/2023/gc/d2gc04547h
4. https://wyss.harvard.edu/news/a-better-way-to-make-rna-drugs
5. https://wyss.harvard.edu/news/daniel-wiegand-on-the-rna-revolution/